Miscalculation
by Chibi no Curse
Summary: A slight miscalculation lands a shrunken Shinichi in the past, where he accidentally prevents his counterpart from being shrunk. Everything has a consequence; Conan Edogawa? Well, he's going to have have to deal with the aftermath.
1. Chapter 1

Disclaimer: I do not own Detective Conan or Magic Kaito.

**Miscalculation**

_Prologue_

Ran Mouri strolled leisurely into Tropical Land, an amusement park that her childhood friend Shinichi had agreed to take her to. (Of course she didn't threaten him with physical violence or anything to get him to agree. Who did you think she was?)

"Oy! Ran!" She turned around at the shout, having recognized it as said childhood friend's voice.

Shinichi ran up to her, somewhat breathless.

"Sorry, am I late? There was a little bit of traffic and there was a really long line and–" Shinichi abruptly cut off having noticed something out of the ordinary.

"Hey, who's this?"

He crouched down to the ground and stared curiously at the little boy that was shyly clutching Ran's hand. Ran blinked for a moment, confused, before she realized what Shinichi was talking about. She smiled happily and explained, gesturing cheerfully at the child.

"Oh, this is Conan-kun. He's staying with me while his parents are in America. Since his parents are friends of the family, I thought it would be a good idea to let him stay with me."

Ran gently pushed Conan towards Shinichi, encouraging him to greet her childhood friend.

"Say hi, Conan-kun."

The aforementioned child flushed slightly, hiding behind Ran. "H-Hi." The shy seven year old stuttered, red coloring his cheeks.

Shinichi grinned and patted the kid on the head. "Ah, so that's it! Well, nice to meet you then, Conan-kun!"

The seven year old smiled uncertainly, managing a quiet laugh.

"Ahaha... nice to meet you, Shinichi... niichan." His words sounded somewhat unsure, but that could be accounted for the child's nervousness at meeting a new person.

As Shinichi straightened to talk to Ran, he missed Conan's abrupt change of expression to exasperated.

The two teens walked through the amusement park, Shinichi babbling on and on about Sherlock Holmes and Ran unhappily listening, although not paying complete attention to the high school detective's words.

"Aha!" Ran suddenly shouted too loudly, interrupting Shinichi's tirade. "There's a ride! It's called the Mystery Coaster; I think it'll be fun to ride!"

She grabbed her friend by the arm and lead Shinichi down towards the ride. Conan reluctantly followed behind, annoyed but relieved that his older sister figure had stopped the high school detective's rant. As they passed the entrance to the amusement park ride, Shinichi blandly noticed a group of three kids attempting to sneak into the ride.

Heh. Kids these days. Shinichi muttered. Trying to get a free ride, huh? He rolled his eyes in annoyance and dutifully allowed Ran to drag him to the attraction.

"Eh? Conan-kun won't be able to ride the roller coaster with us since it's only two people per seat." Ran turned worriedly to the child. "We can go and find another ride instead."

Conan cutely gazed up up at his neechan endearingly, a carefree smile spreading across his cherubic face. "Ne, ne, it's alright Ran-neechan!" He chirped. "You can go have fun on the roller coaster and share a seat with Shinichi-niichan."

The seven year old happily skipped forward "I'll sit by myself." Conan puffed his cheeks, pouting slightly. "I'm old enough to anyway!"

Ran stared down at her little brother figure, unsure about leaving him on his own.

"Are you sure? Because– "

Conan quickly interrupted her before she could finish her sentence.

"Don't worry neechan, I'll be alright!"

Ran sighed in defeat and fondly patted Conan on the head. "Alright Conan-kun, but you have to wait with us!"

The little kid jubliantly bounced on his heels, sing-songing out an affirmative.

"Okay!"

She giggled at Conan's antics and returned her attention to Shinichi, who had been clueless to their entire interaction, once again having been prattling about Sherlock Holmes.

In front of them in the line was a young lady dressed in purple and wearing a pearl necklace. Conan, being the inquisitive joyful little kid he was, trotted over to the aforementioned lady.

"Wah~! That necklace is pretty!"

He jumped up and down, wildly waving his arms around in excitement. The woman's attention instantly swerved to the innocently happy seven year old.

"That must have cost a lot of money!"

The lady giggled, amused at the hyperactive kid's actions.

"No, it wasn't really that expensive. But thanks for the compliment anyway." She smiled and patted Conan on the head before shooing him back with a few words of advice, "You shouldn't wander off without your parents!"

Ran and Shinichi sat down in the coaster, Shinichi still blathering about Sherlock Holmes. Shinichi really was true to his mystery otaku title.

No longer able to stand hearing all these pointless facts and fanboyish mutter any longer, Ran abruptly blew up.

"YOU STUPID MYSTERY OTAKU!" She continued yelling at her friend for babbling about Sherlock Holmes when this was supposed to be a celebration for her winning the karate tournament. Ran brandished a fist threateningly at Shinichi, flames almost blazing around her.

Shinichi jolted backwards immediately, face pale and looking completely aghast. Terrified of Ran's wrath, he unsteadily attempted to apologize to her, stuttering all the while. Appeased at her friend's attempt to cheer her up and atone for whatever he did wrong, she dropped the angry expression.

"Idiot~!" Ran burst out laughing at her friends panicked apologies. "I was just joking!"

The other teen looked offended as he turned to face the front, muttering about never believing her ever again. However, his annoyance at being tricked abruptly flew away when Ran suddenly clutched his hand tightly, squeezing her eyes shut as the roller coaster reached the top and began to descend.

Amid the screaming as they passed through a dark tunnel, a drop of water splashed on Shinichi's face. Water?

He wiped the liquid off of his face, blinking in confusion when he realized what it was. Tears?

Then they exited the tunnel and someone began shrieking, albeit for a different reason this time. Beside one of the women, a man had been decapitated, blood exploding and freely spraying from the severed neck. Murder.

Police sirens split the air, roaring down the street and screeching to a stop at Tropical Land. Law enforcement poured out and immediately began remedy the situation. They arrived at crime scene, removing the body from the roller coaster car and covering it. All witnesses of the murder were quickly confined to the location and prevented from leaving.

"It was only an accident, we don't have time to waste here. Let us leave!"

"Wrong. This was a murder."

A voice rang out clearly amid the panicked whispers of the crowd.

All attention abruptly fixed onto the speaker, who continued his assessment of the situation.

"Also, the murderer was sitting in the same vehicle as the victim. The criminal is among the seven people in the vehicle." Shinichi opened his eyes, revealing confident clear azure.

Megure-keibu fixed an authoritative look on the teen. "Is what you said true, Kudo-kun?"

A shocked wave of whispers immediately began to spread through the crowd, each and every person muttering in recognition of the famous high school detective's name.

One of the police uncovered a bloody knife in Aiko's, the victim's fiance, bag. "Alright, arrest her."

"Hang on a moment, Megure-keibu! She isn't the murderer!" Everyone faced the teen detective in shock. "If she isn't, then who is?"

Shinichi turned and pointed at one of the suspects. "The murderer... is YOU!" Ignoring the girl's panicked protests that she hadn't killed Kishida-san, the murdered victim, he revealed the truth in his deduction and accurately reconstructed the murder.

Meanwhile, in the back of the crowd, Conan impatiently tugged on Ran's shirt. "Ran-neechan, I'm hungry. Can we please leave?" Ran gazed down at the pleading face of the child.

"I'm sorry Conan-kun, but we can't leave until this case is solved." Oddly, Conan's face suddenly lit up.

"Oh, okay then."

She was about to turn around, somewhat confused at Conan's lack of reaction to murder when Conan continued speaking.

"In that case, the neechan with the pretty necklace killed him."

Ran barely managed to find her voice. "E-Eh, Conan-kun, why do you say that?"

The child smiled cutely and began to explain his reasoning in a commonplace everyday tone.

"That's because she put her bag behind her back when they were buckling themselves in. So she could slip out from the roller coaster's safety bar really easily." He looked pensive for a moment. "That's not very safe." The seven year old suddenly perked up. "But that way, she could have killed the guy. And..."

His deduction matched Shinichi's almost word for word, albeit with simpler vocabulary.

"...and her necklace is gone. That's how she carried in the murder weapon."

Apparently, he had said this sentence rather loudly and the police, along with Shinichi, spun around to face the innocent looking seven year old in complete shock.

"..." Shinichi stuttered a few times before he recovered, turning serious.

"Actually, I can explain that." He continued the pseudo enactment of the murder.

"As for the evidence, like Conan-kun said, you used your necklace." He held up a bag with the missing pearls and a hook. "This should be enough to prove it."

The accused, a woman by the name of Hitomi, was speechless. Shinichi continued his deduction.

"Also, you already knew that Kishida-san was going to die, so you started to cry before you killed him. There are still tear traces on the sides of your face. If you didn't start crying before or after riding the roller coaster, then the tear tracks shouldn't be flowing sideways."

Her eyes flicked to the sides of her face and she collapsed to her knees and began to cry, spilling out her sob story and the reason why she had killed Kishida.

"Oy, Ran! Stop crying!" Ran turned to her childhood friend, tears staining her cheeks. "How can you be so calm?" She angrily demanded, glaring at him through her sobs. Shinichi rubbed the back of his head, looking sheepish and smiling slightly. "I've been to so many of these types of scenes, I'm already used to them!"

"That's terrible!" Ran interjected fiercely.

Shinichi was about to reply when something tugged on his pant leg. "Shinichi-niichan!" Conan pouted and puffed his cheeks cutely, looking up at him beseechingly.

"I'm hungry! Can we go somewhere to eat?"

The teenager blinked, confused, blankly staring at the innocent wide eyes of the cherubic seven year old. He had forgotten that the kid was even there.

"Oh! I'm sorry Conan-kun." Ran rubbed her eyes to dry them. "You told me earlier that you were hungry. I must have forgotten."

She managed a smile.

"We can go eat. Shinichi's going to pay for it, right?"

The karate champion fixed her friend with a heated glare. Shinichi laughed nervously and inched away slightly. "Y-Yeah, sure." He forced a somewhat unnatural looking grin. "No problem!" He warbled too loudly, his voice a few octaves too high.

His face dropped the fake smile when Ran turned away to assure Conan that they would get food.

Jeez, Ran was scary!

**A/N**

Plotbunny attack. I'll explain Conan-kun later and flesh out the rest of this story.

Yeah, everyone pretty much forgot about Conan's input on the case already. And Shinichi just missed his chance to be shrunk. Joy. Now he's still full of himself. It'll be up to Conan to knock down Shinichi's ego a few notches.

Input? Comments? Ideas? I'd like some help for future events in this story. I don't want to write about every single case that has been solved in Detective Conan... that would be boring and would take too long. Meh.

…Actually, I think I'll write future events based on review input and ideas. So, any good ideas?


	2. Chapter 2

** g was better then than it is now.**

Disclaimer: I do not own Detective Conan or Magic Kaito.

**Miscalculation**

_Chapter One_

"Well, that worked out wonderfully."

Conan grouched as he ran a hand through his hair. Jeez, who knew that he was such a glory hound back then? His counterpart's massive ego really wasn't something he wanted to deal with on a daily basis.

The sound of a T.V. carried past, another news report about Shinichi Kudo's latest case followed by fangirlish squealing invaded his ears.

"..."

He palmed his face and slumped against the table, a depressing aura infecting his surroundings.

"...I think I'd rather be stuck supervising Kaitou KID and his heists."

He miserably peeked through the gaps of his fingers, loudly groaning and muttering unhappily. This really sucked... he'd certainly prefer to be stuck hanging around KID instead. At least he wouldn't have to deal with an inflated ego.

This guy – his counterpart in this universe – was a complete and utter _dork_. Not to say that he hadn't been anything like that in the past, but to have to deal with himself at that phase of his life was utterly mortifying and excessively annoying. Especially with that stupid expression that surfaced on his past self's face when he was hearing about himself and his dubbed 'amazing-ness' and praised as the savior of the Beika police force.

Huh. No wonder the guy had such an inflated ego...

Conan passed a hand over his face, groaning in exasperation. Maybe it hadn't been such a great idea to delay the Black Organization. Although it hadn't been intentional. He had just wanted to keep an eye on his counterpart and possibly prevent his shrinking. However, he would admit that he hadn't expected that Ran would actually fall for his quick fib. After all, he had just mentioned someone that he vaguely remembered that Ran might have known. In his world at least. It was a relief that it had actually worked. But in his defense, he wasn't really lying to his childhood friend. The person he had claimed relation to actually was some obscure distant cousin somewhere way back in his family tree that he barely even knew.

He sighed and scanned over the day's newspaper.

It appeared that the rules of reality really didn't apply here.

…

Maybe he had been spending too much time around KID. Especially since the white-clad thief was known for his way of breaking the rules of reality on a daily basis.

He scoffed, mussing his hair and sipping some coffee that he had taken from the kitchen.

Hopefully Ran wouldn't check the coffee maker or the can of coffee grounds in the cupboard and notice the depletion in the supply of coffee or filters. If she did, he'd probably be scolded for drinking coffee because 'caffeine was bad for little kids!' and then he'd be permanently banned from the kitchen unless he was supervised. And he couldn't live without his coffee!

But that was only in the worst case scenario. For the best, Ran would most likely lecture her father for drinking more coffee than usual and continue on with her daily business without even suspecting Conan.

A series of thumping sounds announced that Ran had just woken up and was going to the kitchen to make breakfast. Conan quickly downed the cup of caffeine-filled goodness and crumpled the paper cup up and disposed of it in the trash can.

It had been a good thing that he had already put away the items he had used to make the coffee and cleaned off the coffee percolator. Otherwise, he would have risked being discovered before he had been here for barely two days.

Muffled scuffling noises from beside him indicated that the moronic Kogoro Mouri was starting to wake up.

Conan sighed mutely, clapping a hand to his face. He blandly stared at the doorknob of the room he was forced to share. Spending time with the Mouri household again was not something he wanted to relive again (specifically, having to room with Kogoro Mouri). If it weren't for the fact that his counterpart already lived there, he would have chosen to stay in his own house.

He sighed painfully and swung open the door, secretly checking the hall for any other occupants.

Then, Conan faked a yawn and trotted towards the bathroom to brush his teeth. Rubbing his eyes blearily, he jumped up and yanked the at the door, it swinging open with an abrupt thump and whoosh of air. Ignoring Kogoro's muffled squawk as he inattentively collided face first with the door and dropped backwards with a thud, Conan slammed the door shut and hopped up on to a stool.

Stupid height. Why couldn't he be taller?

The seven year old muttered under his breath and leaned over the sink, meticulously squeezing out some toothpaste on his toothbrush. He glared at the mirror, not particularly happy about his life at the moment.

Sure, this world's Ran was really nice (like always), but her father was still moron and an idiot. Just how exactly had the brainless man become a detective in the first place? The worst part was that his counterpart – Shinichi Kudo, the brilliant and renowned high school detective – was an egocentric _dork_. He had been nothing like he should have been – modest but superior and incredibly intelligent – and Conan had found himself sorely disappointed to see his counterpart cackling like a maniac and running around with a moronic full-of-himself expression. (Even though he had done the exact same thing in his past, but still!)

Conan scrunched up his face in disgust and spat out the toothpaste foam into the sink, rinsing his mouth out and replacing his toothbrush back into its holder.

He scrutinized his expression in the mirror, pursing his lips in thought. If this reality's Shinichi just downsized his massive ego, then he'd be a marginally better detective than he was now. Fans cooing and fawning over him probably – no, _definitely_ – made it worse. Pity no one else seemed to notice.

The pint sized detective sighed and hopped off of the step stool and trotted out the door, absentmindedly stepping over the swirly eyed Kogoro Mouri. Apparently the man didn't have very much resistance to blunt trauma. He briefly considered the idea of shaking the man into consciousness but quickly discarded the thought. Nah, the moronic 'famous detective' could take care of himself. Not to mention that Ran would eventually come around and rouse her clueless father.

Conan muttered inaudibly under his breath. Speaking of which, he still didn't understand why people automatically just assumed that children were harmless and didn't know anything. Just because he was a kid didn't mean that he was dumb and hyperactive. People underestimated him way too much. Even Ran treated him like a clueless little kid, both in this reality and his own. If only someone would give him a chance for once!

With that, Conan went to eat breakfast. No reason to hang around and brood over pointless things. People would learn to at least take his observations into consideration one day in the future. Most likely when he was older. (Although he already was, in a sense. Maybe taller?)

Or maybe when he was in high school. Which would make that entirely pointless. (Because he already was. Or should be.)

Conan snorted. In that case, perhaps he should enter a high school instead. But the problem was that if he entered Teitan High School or Ekoda High School, it would be odd. Conan had to admit that he wouldn't want to have to deal with the painfully simplicity of elementary, but, quite grudgingly, he also realized that he would stand out in the high school. A three to four-foot tall high school student would probably really stand out from the other students.

Really really stand out.

Mostly because he'd be less that _half_ the size of all the other students.

Conan sighed unhappily. Elementary school it was. Great. More simple addition, yay.

…

Well, unless he actually acted his age and stopped toning down his intelligence. Then he'd be branded as a genius and moved up several grades.

Conan paused and considered it for a moment. Maybe that was a good idea.

But it meant that he was taking a chance of being discovered much faster than he would be if he faked being a brainless child with spurts of intelligence. (specifically at crime scenes.) And plus, since he had basically been lying through his teeth when he had told Ran who his parents supposedly were, he would be found out sooner or later.

Conan gritted his teeth and rapidly jumped up and down in a rare show of a childish tantrum. No fair! Why couldn't he just be a smart genius seven year old without people doubting his identity? He didn't particularly enjoy having to shrink his vocabulary and act sickeningly cute and innocent to avoid suspicion. It was demeaning!

He huffed angrily and puffed his cheeks out, pouting. He would certainly rather risk being discovered than worry about being the first and youngest person to die of boredom. At least then he'd die in a more conventional way.

…

Well, only if death by flaming soccer ball moving at supersonic speeds to the face counted as a conventional way to die. (Most likely what this world's Shinichi's reaction would be when he found out that another teenage male had been living with his childhood friend and possible crush.)

Pausing, Conan flushed and looked sheepish for a moment, realizing how childish and stupid that entire scenario had been. When exactly had he starting acting more like the age he appeared to be?

...It was probably a side effect from pretending to be a child for so long. Maybe the time he had spent with the kiddie troupe was starting to rub off on him.

"…Conan-kun?"

Conan stiffened and slowly turned around, wide eyed in shock. Had Ran been there the entire time he had been throwing a temper tantrum? Oh gosh... he probably thought he was mentally retarded or messed up in the head now...

"…eep."

Ran blinked in confusion, sending a curious glance at the doorway. She could have sworn she'd seen Conan stomping around and darkly muttering in the hallway a second ago. But then she had blinked and there was no one there except for some traces of dust. And there was no way a little kid could disappear that fast. Maybe it was all just in her head...

Hm. Speaking of which, shouldn't she be waking up otou-san now? Her father was probably lazing in bed again and snoring loud enough to raise the dead. She shook her head and briskly strode down to her father's room. Parents these days...

A shriek gusted from the hallway with the force of freight train, nearly bowling Conan over from the sheer volume itself.

What was _that_?

A string of lectures and disapproving shouts crashed through the air, reaching Conan's ears. He winced. Ran had most likely just found her father sprawled on the floor. Peeking through the doorway, he was met with the sight of Ran chastising her father – who had a sizable lump on his head and a door imprint in his face – and scolding him for sleeping on the floor.

Conan cringed and backed into the kitchen. Maybe he shouldn't have left the moron on the floor...

Ran patted Conan on the head gently, lightly chastising him not to get lost or talk to any strangers, her foreboding anger at her father completely forgotten at this point. Since Conan hadn't been enrolled into school yet, she had no choice but to leave him at home.

As Ran walked out the door and out of sight, Conan dropped his cheerful smile and trotted past his room, scooping up a cap and a blonde wig he had purchased at one point when Ran wasn't looking. Where he was going, he didn't want to risk recognition later on.

He donned the wig, yanking the cap down over his face and taking off his glasses. When he checked his appearance in the mirror, a young blond boy stared innocently back, completely unrecognizable.

Conan smirked.

This was just how much better at disguising he was than KID. Especially since he didn't even need latex masks or voice changers. All he needed was a hat or some other easily accessible item to render himself unrecognizable. And when it came to voices, it wasn't really necessary for him to have a wide range of voice pitches. He used what he had available and he was good at it.

Although, that also meant that he wasn't as great in the impersonation department as KID was. But it didn't really matter anyway. Besides, it wasn't like he had any future plans to impersonate or replace anyone in the near future.

Right?

**A/N**

Yeah, late update. Sorry.

I finished this chapter up a while ago, but just didn't have time to post it. Ideas are greatly appreciated. Maybe you'll see it in one of the chapters? (hint, hint)


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